Alpha-2 Zone
This zone consists principally of alpha-2 macroglobulin (AMG) and haptoglobin. There are typically low levels in haemolytic anaemia (haptoglobin is a suicide molecule which binds with free haemoglobin released from red blood cells and these complexes are rapidly removed by phagocytes). Haptoglobin is raised as part of the acute phase response, resulting in a typical elevation in the alpha-2 zone during inflammation. A normal alpha-2 and an elevated alpha-1 zone is a typical pattern in hepatic metastasis and cirrhosis.
Haptoglobin/haemaglobin complexes migrate more cathodally than haptoglobin as seen in the alpha-2 - beta interzone. This is typically seen as a broadening of the alpha-2 zone.
Alpha-2 macroglobulin may be elevated in children and the elderly. This is seen as a sharp front to the alpha-2 band. AMG is markedly raised (10-fold increase or greater) in association with glomerular protein loss, as in nephrotic syndrome. Due to its large size, AMG cannot pass through glomeruli, while other lower-molecular weight proteins are lost. Enhanced synthesis of AMG accounts for its absolute increase in nephrotic syndrome.
AMG is mildly elevated early in the course of diabetic nephropathy.
Read more about this topic: Serum Protein Electrophoresis
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